J Biomed Phys Eng 2012; 2(4) www.jbpe.org Nanomaterial Containing Wall Paints Can Increase Radon Concentration in Houses Located in Radon Prone Areas Haghani M. 2 , Mortazavi S. M. J. 1, 2* , Faghihi R. 3 , Mehdiza- deh S. 3 , Moradgholi J. 4 , Darvish L. 5 , Fathi-Pour E. 5 , Ansari L. 5 , Ghanbar-pour M. R. 3 1 The Center for Radio- logical Research, Shiraz University of Medical Sciences, Shiraz, Iran 2 Department of Medi- cal Physics and Medical Engineering, School of Medicine, Shiraz Univer- sity of Medical Sciences, Shiraz, Iran 3 Radiation Research Center, Mechanical En- gineering School, Shiraz University, Shiraz, Iran 4 Ph.D student of nano- materials, Department of Materials Engineer- ing, Isfahan University of Technology, Isfahan 84156-83111, Iran 5 Master Student, Stu- dent Research Commit- tee, School of Medicine, Shiraz University of Medical Sciences, Shi- raz, Iran *Corresponding author: Prof. Mortazavi S. M. J., Ph.D Medical Physics & Medi- cal Engineering Depart- ment, The Head The Center for Research on Radiological Scienc- es, The Head Medical Physics & Medi- cal Engineering Depart- ment School of Medicine, Zand Street Shiraz University of Medical Sciences E-mail: mmortazavi@ sums.ac.ir ABSTRACT Background: Nowadays, extensive technological advancements have made it possible to use nanopaints which show exciting properties. In IR Iran excessive radon levels (up to 3700 Bq m–3) have been reported in homes located in radon prone areas. Over the past decades, concerns have been raised about the risk posed by resi- dential radon exposure. Objective: This study aims at investigating the effect of using nanomaterial con- taining wall paints on radon concentration in homes. Methods: Two wooden model houses were used in this study. Soil samples from Ramsar high background radiation areas were used for simulating the situation of a typical house in radon-prone areas. Conventional water-soluble wall paint was used for painting the walls of the 1st house model; while the 2nd house model was painted with the same wall paint with montmorillonite nanoclay. Results: Three days after sealing the house models, radon level was measured by using a portable radon survey meter. The mean radon level inside the 1st house model (conventional paint) was 515.3 ± 17.8 Bq/m3 while the mean radon concentra- tion in the 2nd house model (nano-painted house model) was 570.8 ± 18.5 Bq/m3. The difference between these means was statistically signiicant (P<0.001). Conclusion: To the best of our knowledge, this study is the irst investigation on the effect of nano-material containing wall paints on indoor radon concentrations. It can be concluded that nano-material-containing wall paints should not be used in houses with wooden walls located in radon prone areas. Although the mechanism of this effect is not clearly known, decreased porosity in nano-paints might be a key fac- tor in increasing the radon concentration in homes. Keywords Radon, Radon Prone Areas, Wall Covering, Paint, Nano-montmorillonite, Nanoclay Introduction R adon, a radioactive gas produced by the disintegration of ura- nium in Earth’s crust, can escape into the air and accumulate to harmful concentrations in residential places. However, outdoor radon is rapidly diluted and hence is not a common concern [1]. The most common isotopes of radon are Radon-222 (radon) and radon-220 (thoron). Although there is no large scale data on the incidence of radon- related lung cancers in Iran, long-term exposure to high concentrations of indoor radon has been reported to be the second leading cause of Short Communication I